Not quite four-and-a-half years ago, I snagged a Roomba Scheduler off of Woot.com. After about a year, though, the battery capacity had fallen so precipitously that it barely ran at all, and it didn't seem to be getting much out of being docked on the home base. At the time, I just figured the battery was kaput, so I ordered a new one, swapped it, and ... no dice. Roomba would charge fine directly from the wall, but not off the home base. This suggested a problem with the home base, but, at the time, I didn't have the information to confirm this (because it could still have been the Roomba's connection to the home base, instead of something in the home base, itself).

Although the model and symptoms aren't quite the same, that turned out to be my problem: the home base was cooked.

The long and the short of what I needed to confirm that:

A voltmeter. I have a cheap multimeter laying around someplace, but can't find it. I wound up buying a new multimeter at Home Depot, but Radio Shack had a cheap one I should probably have grabbed, instead.

A 4.7k ohm resistor, good for at least 1/4 watt. I bought some 1/2-watt 4.7k ohm resistors at Radio Shack. They worked fine

A means of connecting the resistor to either the probes of your meter, or to the contacts of the Roomba home base. One approach is pictured in the article linked above. I grabbed a bunch of alligator-clipped test leads while I was at Radio Shack.

With each end of the resistor clipped to a different probe, it was pretty trivial to check the voltage being put out by my home base. The good/bad news for me is that, instead of rising to about 22.5 volts, my base was falling to 2 volts. Well, as they say, there's my problem.

When the new base arrived, I double checked the voltage on it, just for good measure: it puts out a bit over 20. Not quite as high as it ought to be, but I'm not sure what the tolerance is on that number, and it sure seems to have done the trick: Roomba's been busily eating dust bunnies and getting caught on cables for over a week, now.
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The World Is Full of Mystery and Wonder

2012.02.23 11:09 - Miscellanea

People, I don't know if you knew already, but I just found out squids can fly. Like rockets.

The second, and shorter, was that I visited the Henry Ford museum ages and ages ago with my parents and sister. It's been more than two decades, but exactly how much more I'm not sure. All these years on, the things I remember are:

the museum is huge,

related to (1), by the end of the day, I was very tired and my feet hurt

it would be pretty neat to go back.

The first thing, though, is that I'm surprisingly pessimistic about the ability of technology to fundamentally change the human nature. Not to say that technology cannot (or has not) done great things to improve the human condition--personally, I love indoor plumbing and electricity--but people remain, well, people. It seems unlikely any amount of technology will ever change human nature from the venal, petty sort of thing it is. Which I suspect is a place where my opinions and Mr. Stross's part company. (One of many, I'm pretty sure.)

Not really my strong point, but I thought I should be looking for a hotel for Homecoming, if I'm going. ISTR a consensus last year to find somewhere other than the Best Western. Was a decision made/is anyone else going/etc?
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